On May 2, With about 400 to 500 men, Sumter laid siege to Ft. Granby, commanded by Maj. Maxwell, of the Prince of Wales Regt. Maxwell had 340 men, including 60 regulars (mostly Provincials, and including soldiers from Maxwell’s own regiment the Prince of Wales Volunteers). As well with him were some loyalists, including a militia unit from the Orangeburg area, under Capt. Samuel Tolless. Maxwell’s artillery at the fort consisted of 2 twelve-pounders, and 3 or 4 smaller cannon. Sumter had written Greene on May 2nd requesting a field piece and ammunition from Greene, and a six-pounder was immediately sent. He sent Greene 10 wagons of meal, and in a few days received back ammunition in those same wagons, plus the cannon. Sumter then took his main force, and the cannon, and moved against Orangeburg, while, at the same time, leaving a detachment, under Col. Thomas Taylor to besiege the fort.

On May 13, Lt. Col. Henry Lee and a large force left Fort Motte on a mission to Fort Granby. Fort Granby was a strong British post, commanded by Maj. Andrew Maxwell, that held 292 Tories and 60 mounted German mercinaries. The fort was actually a fortified fram building. Lee knew that Maxwell was not a strong military leader, devoting most of his time to collecting plunder.

On May 14, Marion and Lee, with 400 to 500 infantry, arrived at Granby on the evening of the 14th. Already there besieging the post was a small detachment of Sumter’s under Col. Thomas Taylor. Lee arrived to within 600 yards of the fort and set up a 6-lb. gun. He was to wait until morning before beginning his attack. After the morning fog lifted, he ordered an artillery barrage on the fort and moved his Legion infanbtry forward. They fired a volley of musketfire at the fort. Having shown the strength of his forces, Lee decided to negotiate a surrender. Maj. Andrew Maxwell, commander of the fort, stated that he would surrender only if he and his men could keep their plunder, taken from the local countryside. Lee agredd to these terms.

On May 15, after the early morning fog cleared, he ordered the gun to fire and then moved forward with his men. Maxwell's pickets were quickly overrun. Lee summoned Maxwell to surrender. Maxwell stated that he would accept the surrender on 2 conditions. They were that he and his men could keep their plunder and the garrison would be allowed to withdraw to Charleston as prisoners of war until exchanged.

Lee had sent a small cavalry force to screen in the direction of Camden, looking for signs of Rawdon and his reinforcements. Lee received word from the cavalry screeners that Rawdon had been spotted crossing the Santte River at Nelson's Ferry and was approaching Fort Motte. Lee was in a hurry so he sent word to Maxwell that the original; surrender terms would be accepted.

This was at noon of May 15. The British garrison contained 60 British regulars (including some Hessians and men from Prince of Wales Regiment), 280 Loyalist, two artillery pieces, and included numerous wagons. Lee gives the garrison’s strength as 360, and that most of these were loyalists. Knowing that Lt. Col. Francis Rawdon, who was at Canden, had been requested from the Tories and that he may be on his way, allowed horses belonging as private property to individuals of the garrison to be kept by them, while officers were allowed their side arms as well. Maxwell himself was permitted to retain two wagons of private baggage. The Germans objected to this and temporarily suspended the surrender. These taken were to march to Charleston as prisoners of war on parole.

Before noon, the capitulation was signed and Maxwell moved 2 wagons full of his personal plunder. The fort was found to be well stocked with stores, which under terms of capitulation, were left for the Americans. Among the equipment that was captured was 192 muskets, 86 bayonets, 63 rifles, 8,928 musket cartridges, 100 cartridge boxes, 3,000 flints, 120 lbs. of powder, 328 lbs. of lead, 20 12-lb. canister shot, and 1 drum.

Sumter, angered at the terms Lee gave and by having the prize of Granby taken from him, for about the next month, offered his resignation, saying that his old wound troubled him. Greene, each time, respectfully refused it, while giving him a sizable share of some of the munitions and stores captured at Granby, He also gave Sumter some of the slaves taken from loyalists there, which then Sumter used as pay for his 10 months men. After the surrender, Lee moved to besiege Augusta. Marion, meanwhile, headed back to his base of operations above the Santee with a mind to taking Georgetown.